• Carbon letters
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• 제11권4호
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• pp.325-331
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• 2010

This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets ($xGnP^{TM}$) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.

• 전력전자학회논문지
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• 제6권6호
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• pp.489-497
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• 2001

병렬로 구성되 UPS 사이에 파라미터 불일치에 따른 순환전류와 전압리플이 발생되어지는데, 이들은 전체 UPS 시스템의 고장 및 신뢰성 저하를 유발한다. 본 논문에서는 이러한 문제점들은 Double 위상동동기기와 능동 다중인 터페이스 리액터를 사용하여 해결하였다. 또한 ADSP21061을 사용하여 제어기를 디지털적으로 구현하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.276-280
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• 1998

This paper proposes a harmonic a harmonic reduction technique of the parallel-connected twelve-pulse thyristor rectifiers. The proposed system is an improvement over the diode rectifier system with an active interphase reactor [2]. In this scheme, a low KVA (0.15 Po (PU) ) active current source injects a triangular current into an interphase reactor of a twelve-pulse thyristor rectifier along the phase delay angle. The current injection results in near sinusoidal input current with less than 1% THD. Detailed analysis of the proposed scheme along scheme along with design equations is illustrated. Simulation results verify the concept.

• 한국세라믹학회지
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• 제49권4호
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• pp.295-300
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• 2012

SiC-based ceramic matrix composites show many advantages over their monolithic ceramic counterparts, which makes them potential candidates for applications in various fields. Depending strongly on the chemical composition and microstructure of the fiber reinforcement, matrix as well as the fiber/matrix interphase in the material, the properties of ceramic matrix composites(CMCs) are highly tailorable. In this paper, the latest progresses in the interphase design, matrix modification and fiber reinforcement decoration of CMCs are reviewed, their effects on the properties of the CMCs are introduced.

• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1365-1375
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• 2000

Two phase flows have been numerically calculated to analyze plume characteristics and liquid circulation in gas injection through a porous plug. The Eulerian approach has been for formulation of both the continuous and dispersed phases. The turbulence in the liquid phase has been modeled using the standard $textsc{k}$-$\varepsilon$ turbulence model. The interphase friction coefficient has been calculated using correlations available in the literature. The turbulent dispersion of the phase has been modeled by the "dispersion Prand시 number". The predicted mean flows is compared well with the experimental data. The plume region area and the axial velocities are increased with the gas flow rate and with the decrease in the inlet area. The turbulent intensity also shows the same trend. Also, the space-averaged turbulent kinetic energy for various gas flow rates and inlet areas has been obtained. The results are of interest in the design and operation of a wide variety of materials and chemical processing operations.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.169-169
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• 2017

Due to key roles for the electrochemical stability and charge capacity the solid-electrolyte interphase (SEI) has been extensively studied in anodes of a Li-ion battery cell. There is, however, few of investigation for cathodes. Using first-principles based calculations we describe atomic-level process of the SEI layer formation at the interface of a carbonate electrolyte and $LiMn_2O_4$ spinel cathode. Furthermore, using beyond the conventional density functional theory (DFT+U) calculations we examine the work function of the cathode and frontier orbitals of the electrolyte. Based on the results we propose that proton transfer at the interface is an essential mechanism initiating the SEI layer formation in the $LiMn_2O_4$. Our results can guide a design concept for stable and high capacity Li-ion battery cell through screening an optimum electrolyte fine-tuned energy band alignment for a given cathode.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.506-509
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• 2001

A high power U.P.S system utilizing the parallel connection of low power U.P.S is developed. For the purpose of elimination the circular current between U.P.S.s, a digital circuit is employed. Furthermore a double phase synchronization and an interphase reactor are used to eliminate the circular current and the voltage ripples caused by the system parameter unbalances of parall connected U.P.S.s. The digital controller is implemented with ADSP21061 as aspect of a functional convenience.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.97-97
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• 2016

Development of advanced Li-ion battery cells with high durability is critical for safe operation, especially in applications to electric vehicles and portable electronic devices. Understanding fundamental mechanism on the formation of a solid-electrolyte interphase (SEI) layer, which plays a substantial role in the electrochemical stability of the Li-ion battery, in a cathode was rarely reported unlike in an anode. Using first-principles density functional theory (DFT) calculations and ab-initio molecular dynamic (AIMD) simulations we demonstrate atomic-level process on the generation of the SEI layer at the interface of a carbonate-based electrolyte and a spinel $LiMn_2O_4$ cathode. To accomplish the object we calculate the energy band alignment between the work function of the cathode and frontier orbitals of the electrolyte. We figure out that a proton abstraction from the carbonate-based electrolyte is a critical step for the initiation of an SEI layer formation. Our results can provide a design concept for stable Li-ion batteries by optimizing electrolytes to form proper SEI layers.

• 한국전산구조공학회논문집
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• 제26권6호
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• pp.423-430
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• 2013

본 연구에서는 탄소나노튜브와 폴리프로필렌 기지 간 계면결합력과 나노튜브의 국부적 응집에 따른 나노복합재의 탄소성 거동 변화에 대한 파라메트릭 연구를 수행한다. 나노복합재의 탄소성 거동 예측을 위해 분자동역학 전산모사를 수행하고, 분자동역학 결과와 Mori-Tanaka 모델을 적용한 비선형 미시역학 모델을 연계하여 나노복합재 내 흡착계면의 탄소성 거동을 역으로 도출하는 2단계 영역분할 기법을 적용하였다. 미시역학 모델에서는 시컨트 계수방법을 Mori-Tanaka 모델에 적용하여 나노복합재의 비선형 거동을 예측하는 방법을 적용하였으며, 나노튜브와 기지 간 재료계면의 불완전 결합을 고려하기 위해 변위 불연속 조건을 적용하였다. 흡착영역을 고려한 미시역학 모델을 통해 흡착계면의 유무 및 재료계면 결합력 변화 그리고 나노튜브의 국부적 응집현상에 따른 나노복합재의 응력-변형률 관계를 예측하였다. 그 결과 나노튜브의 국부적 응집이 나노복합재의 강화효과를 저하시키는 가장 중요한 변수임을 확인하였다.

• Clinical and Experimental Reproductive Medicine
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• 제24권3호
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• pp.335-340
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• 1997

Fluorescence in situ hybridization (FISH) techniques allow the enumeration of chromosome abnormalities and from a great potential for many clinical applications. In order to produce quantitative and reproducible results, expensive tools such as a cooled CCD camera and a computer software are required. We have developed a Chromosome Image Processing System (Chips) using FISH that allows the detection and mapping of the genetic aberrations. The aim of our study, therefore, is to evaluate the capabilities of our original system using a black-and-white video camera. As a model system, three repetitive DNA probes (D18Z1, DXZ1, and DYZ3) were hybridized to variety different clinical samples such as human metaphase spreads and interphase nuclei obtained from uncultured peripheral blood lymphocytes, uncultured amniocytes, and germ cells. The visualization of the FISH signals was performed using our system for image acquisition and pseudocoloring. FISH images were obtained by combining images from each of probes and DAPI counterstain captured separately. Using our original system, the aberrations of single or multiple chromosomes in a single hybridization experiment using chromosomes and interphase nuclei from a variety of cell types, including lymphocytes, amniocytes, sperm, and biopsied blastomeres, were enabled to evaluate. There were no differences in the image quality in accordance with FISH method, fluorochrome types, or different clinical samples. Always bright signals were detected using our system. Our system also yielded constant results. Our Chips would permit a level of performance of FISH analysis on metaphase chromosomes and interphase nuclei with unparalleled capabilities. Thus, it would be useful for clinical purposes.